Structure and electrochemical hydrogen storage characteristics of Ce-Mg-Ni-based alloys synthesized by mechanical milling

Abstract

The substituting Mg with Ni and milling as-cast alloy with Ni were adopted to obtain nanocrystalline/amorphous CeMg11Ni+x wt.% Ni (x=100, 200) alloys and promote the electrochemical hydrogen storage performances of CeMg12-type alloys. Analyzing the structural features of the alloys provided a mechanism for ameliorating the electrochemical hydrogen storage properties. The electrochemical tests demonstrated that all the alloys just needed one cycle to be activated. Rising Ni proportion had an obvious role on charge-discharge reaction. The discharge capacities of the as-milled (60 h) alloys increased sharply from 182.0 mAh/g for x=100 alloy to 1010.2 mAh/g for x=200 alloy at current density of 60 mAh/g. Furthermore, milling time largely determined the performances of electrochemical reaction. The discharge capacity continued to grow along with prolonging milling time, while the cycle stability obviously decreased for x=100 alloy, and first declined and then augmented for the x=200 alloy with milling time extending. In addition, there was an optimal value with milling time varying for the high rate discharge abilities (HRD), which was 80.3% for x=100 alloys and 86.73% for x=200, respectively.